Expansible anchors of that kind are known per se. The known expansible anchors have an anchor bolt provided with a screw thread at the rear end and with an expansion cone at the front end. The anchor bolt together with the expansion cone may be referred to as the basic anchor part. An expansion sleeve, which is usually divided into expansion portions by means of longitudinal slits, is mounted on the anchor bolt. The expansion sleeve is expanded as a result of being pushed up on the expansion cone and, as a result, it anchors the expansible anchor in a drilled hole. In the known expansible anchors, expansion is brought about by screwing on and tightening a nut on the screw thread of the anchor bolt. The nut presses against the expansion sleeve directly or—by way of a sleeve mounted on the anchor bolt, between the nut and the expansion sleeve—indirectly and, as a result, pushes the expansion sleeve up on the expansion cone, expanding the expansion sleeve. In the case of such expansible anchors it is disadvantageous that they are complicated and consequently expensive to manufacture. It is further disadvantageous that expansion is brought about by screwing on and tightening the nut on the screw thread of the anchor bolt, which is time-consuming and should always be carried out using a torque wrench.
So-called hammer-in anchors are also known, which can be expanded by driving an expansion member into an expansion sleeve. An axial hole in the expansion sleeve of such expansible anchors becomes narrower between the expansion portions so that the expansion portions can be expanded by driving in the preferably conical expansion member. Such expansible anchors are economical to manufacture and can be expanded simply and rapidly by hammer blows with the aid of, for example, a punch and anchored in a drilled hole as a result. Such expansible anchors have the disadvantage, however, that they exhibit no subsequent expansion behaviour, slackening in the event of widening of the drilled hole, for example caused by crack formation, and coming loose.